Fiber products, particularly products made of glass fibers, are typically made as either continuous fibers or discontinuous fibers. Various materials can be applied to these fibers for protecting the fibers from abrasion, for connecting the fibers to each other to form a structural product, and for providing compatibility of the fibers with other materials, such as the compatibility between the reinforcement fiber and a plastic matrix. In the case of insulation products, the fibers are usually bonded together by organic material, such as a phenol/formaldehyde binder, to form a spring-like matrix which can recover after compression during packaging.
The application of the materials to the fibers can take several forms. Continuous fibers can be run through a bath or across a coater to apply a coating to the fibers, such as during the application of a size to continuous fibers. Alternatively, the material can be sprayed onto the fibers. This method is commonly used in the manufacture of insulation products with a rotary process where a cylindrical veil of fibers is met with the sprays of the phenol/formaldehyde binder.
One of the problems with applying aqueous organic binders to cylindrical veils of fibers is that it is difficult to achieve an even dispersion of the binder onto the fibers in the veil. In the past, the spray systems sometimes caused an overspray of material on the fibers, thus wasting spray material and sometimes affecting the quality of the formed fiberized material. In other instances, such spray systems caused an underspray of material onto the fibers, thereby producing a product with unevenly distributed coated fibers having less desirable properties.